Mdm holimah had some flour. She used 20% of the flour to bake a cake and 30% of the flour to bake some cookies. A)what percentage of the flour did she have left. B)what fraction of the flour did she use to bake a cookie?

A)So the total of the flour overall is 100%. 20% was used to bake the cake, and 30% for cookies, so 20+30=50%. To work out what percentage is left, we take away the used amount from the overall percentage, i.e. 100-50=50%. B) A percentage is a number out of 100, e.g. 100%=100/100, 50%=50/100 etc. So she used 30% of the flour to bake cookies: 30%=30/100. Then we need to simplify this fraction: we can see that the highest common factor that goes into both 30 and 100 is 10, so divide each number by 10, and our simplified fraction is 3/10. So she used 3/10 of the flower to bake cookies.